RESUMO
In this study, 3D-printing based on fused-deposition modeling (FDM) was employed as simple and cost-effective strategy to fabricate a novel format of rotating-disk sorptive devices. As proof-of-concept, twenty organochlorine and organophosphorus pesticides were determined in water samples through rotating-disk sorptive extraction (RDSE) using honeycomb-like 3D-printed disks followed by gas chromatography coupled to mass spectrometry (GC-MS). The devices that exhibited the best performance were comprised of polyamide + 15 % carbon fiber (PA + 15 % C) with the morphology being evaluated through X-ray microtomography. The optimized extraction conditions consisted of 120 min of extraction using 20 mL of sample at stirring speed of 1100 rpm. Additionally, liquid desorption using 800 µL of acetonitrile for 25 min at stirring speed of 1100 rpm provided the best response. Importantly, the methodology also exhibited high throughput since an extraction/desorption platform that permitted up to fifteen simultaneous extractions was employed. The method was validated, providing coefficients of determination higher than 0.9706 for all analytes; limits of detection (LODs) and limits of quantification (LOQs) ranged from 0.15 to 3.03 µg L-1 and from 0.5 to 10.0 µg L-1, respectively. Intraday precision ranged from 4.01 to 18.73 %, and interday precision varied from 4.83 to 20.00 %. Accuracy was examined through relative recoveries and ranged from 73.29 to 121.51 %. This method was successfully applied to analyze nine groundwater samples from monitoring wells of gas stations in São Paulo. Moreover, the greenness was assessed through AGREEprep metrics, and an overall score of 0.69 was obtained indicating that the method proposed can be considered sustainable.
Assuntos
Cromatografia Gasosa-Espectrometria de Massas , Hidrocarbonetos Clorados , Limite de Detecção , Compostos Organofosforados , Praguicidas , Impressão Tridimensional , Poluentes Químicos da Água , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação , Compostos Organofosforados/análise , Compostos Organofosforados/isolamento & purificação , Praguicidas/análise , Praguicidas/isolamento & purificação , Hidrocarbonetos Clorados/análise , Hidrocarbonetos Clorados/isolamento & purificação , Cromatografia Gasosa-Espectrometria de Massas/métodos , AdsorçãoRESUMO
In this study, a biosorbent material with characteristics for the adsorption of organic compounds was used for a cork pellet-based bar adsorptive microextraction technique, as a new greener alternative for the determination of organochlorine compounds. Aldrin, chlordane, dieldrin, endrin, lindane, 4,4-DDD, 4,4-DDE, 4,4-DDT, α-endosulfan and ß-endosulfan were analyzed in water samples (drinking water, stream water and river water) with separation/detection by gas chromatography and electron capture detection (GC/ECD). The parameters that can affect the sample preparation efficiency such as desorption solvent and time as well as extraction time and ionic strength were evaluated by multivariate and univariate designs. Cork pellets (10 × Ø 3 mm) were used for the extraction of 15 mL of sample in the optimal conditions: 60 min of agitation with no salt added to the sample, followed by desorption of the cork pellet with 120 µL of ethyl acetate for 30 min. The bar-to-bar RSD out with five different bars showed good results with RSD ≤ 15.6%, allowing the use of simultaneous extractions. LOD and LOQ values ranged from 3 to 15 ng L-1 and 10 to 50 ng L-1 respectively, and the determination coefficients were greater than 0.9869. The target analytes were not detected in the three analyzed samples. Therefore, the recovery study was performed fortifying the water samples. Analyte recovery ranged from 48.7 - 138.2% for drinking water, 40.2 - 128.2% for stream water and 67.5 - 128.7% for river water.
Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Hidrocarbonetos Clorados/análise , Microextração em Fase Líquida/métodos , Praguicidas/análise , Poluentes Químicos da Água/análise , Adsorção , Hidrocarbonetos Clorados/química , Hidrocarbonetos Clorados/isolamento & purificação , Limite de Detecção , Praguicidas/química , Praguicidas/isolamento & purificação , Reprodutibilidade dos Testes , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificaçãoRESUMO
Organochlorine pesticides present in sewage sludge can contaminate soil and water when they are used as either fertilizer or agricultural soil conditioner. In this study, the technique solid-liquid extraction with low temperature purification was optimized and validated for determination of ten organochlorine pesticides in sewage sludge and soil samples. Liquid-liquid extraction with low temperature purification was also validated for the same compounds in water. Analyses were performed by gas chromatography-mass spectrometry operating in the selective ion monitoring mode. After optimization, the methods showed recoveries between 70% and 115% with relative standard deviation lower than 13% for all target analytes in the three matrices. The linearity was demonstrated in the range of 20 to 70 µg L-1, 0.5 to 60 µg L-1, and 3 to 13 µg L-1, for sludge, soil, and acetonitrile, respectively. The limit of quantification ranged between 2 and 40 µg kg-1, 1 and 6 µg kg-1, and 0.5 µg L-1 for sludge, soil, and water, respectively. The methods were used in the study of pesticide lixiviation carried out in a poly vinyl chlorine column filled with soil, which had its surface layer mixed with sludge. The results showed that pesticides are not leached into soil, part of them is adsorbed by the sewage sludge (4-40%), and most pesticides are lost by volatilization.
Assuntos
Hidrocarbonetos Clorados/análise , Extração Líquido-Líquido/métodos , Praguicidas/análise , Praguicidas/isolamento & purificação , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Acetonitrilas , Agricultura , Brasil , Fertilizantes/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Hidrocarbonetos Clorados/isolamento & purificação , Reprodutibilidade dos Testes , Esgotos/análise , Poluentes do Solo/isolamento & purificação , Temperatura , Poluentes Químicos da Água/isolamento & purificaçãoRESUMO
Organochlorine pesticides (OCPs) can cause environmental damage and human health risks since they are lipophilic compounds with high resistance to degradation and long half-lives in humans. As most persistent OCPs have been banned years ago, it is expected to find these compounds at trace levels in environment. Therefore, increasingly sensitive and reliable analytical techniques are required to ensure effective monitoring of these compounds. The aim of this review is to discuss extraction and clean-up methods used to monitor OCP residues in milk, reported in the last 20 years. To carry out this review, an exhaustive bibliographic review was conducted. Despite the disadvantages of conventional extraction and clean-up methods, such as liquid-liquid, solid-phase or Soxhlet extractions, these procedures are still used due to their reliability. New extraction methods, like solid-phase microextraction, matrix solid-phase dispersion or QuEChERS, have not been thoroughly evaluated for OCP determination in milk. Almost all the methodologies analyzed in this review presented good performance characteristics according to the performance acceptability criteria set in SANCO's procedure. Comparison between limits of quantification (LOQ) and detection (LOD), for the reported methodologies, is not always possible due to the heterogeneity of the units. Thus, researchers should take into account an homogenization of LOD and LOQ units, according to the international regulations and MRLs established. Finally, more research is necessary to obtain the ideal methodology for OCPs determination in milk, which comprises the environmentally friendly characteristics of the new techniques and the reliability of the traditional methodologies.
Assuntos
Fracionamento Químico/métodos , Hidrocarbonetos Clorados/isolamento & purificação , Leite/química , Resíduos de Praguicidas/isolamento & purificação , Animais , Contaminação de Alimentos/análise , Humanos , Hidrocarbonetos Clorados/análise , Hidrocarbonetos Clorados/química , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/químicaRESUMO
The presence of organochlorine pesticides (OCPs) in biological and environmental samples has been studied for decades in many countries. Nonetheless, studies in Latin American countries like Colombia have been scarce. Determining the presence of OCPs in breast milk will be of relevance to assess exposures, potential health risks, and for surveillance among Latin American populations. Thirty-two breast-feeding mothers were selected to voluntarily participate in the study. Breast milk samples were analyzed for 10 OCPs (α-, ß-, γ-, δ-HCH, Heptachlor, α-, γ-Chlordane, 4,4' DDT, 4,4' DDE, 4,4' DDD). Milk samples were analyzed using liquid-liquid extraction, followed by sulfuric acid clean-up, and quantified using GC/µECD. Results were confirmed by GC/MS. OCPs concentrations were normalized using fat content. In all but one sample, 4,4' DDE was quantified in concentrations ranging between<17 and 14948 ng g(-1) (ng of OCP per g of lipids), with a mean value of 203 ng g(-1). One woman had 4,4' DDE concentrations that were orders of magnitude above the average concentrations observed worldwide. Concentrations of 4,4' DDE in a second breast milk sample collected in a different time period of lactation from a sub-group of 13 women from the original participants, showed no statistically significant difference with the concentrations found in the first sample. Based on the results obtained from the Persistent Organic Pollutants Global Monitoring Plan report of 2009 of the Stockholm Convention, Colombia ranks fourth from bottom to top in terms of 4,4' DDE average concentrations.
Assuntos
Monitoramento Ambiental , Poluentes Ambientais/análise , Hidrocarbonetos Clorados/análise , Leite Humano/química , Praguicidas/análise , Adolescente , Adulto , Colômbia , Poluentes Ambientais/química , Poluentes Ambientais/isolamento & purificação , Feminino , Humanos , Hidrocarbonetos Clorados/química , Hidrocarbonetos Clorados/isolamento & purificação , Praguicidas/química , Praguicidas/isolamento & purificação , Gravidez , Adulto JovemRESUMO
For cleanup of animal fat before GC analysis of organochlorine pesticides and polychlorinated biphenyls, freezing-lipid filtration with solid-phase extraction and matrix solid-phase dispersion were evaluated to replace the official Brazilian methodology that uses preparative alumina column chromatography. General drawbacks associated with this last technique, such as the use of large amounts of solvent, laborious and time-consuming procedure could be avoided by using these alternative approaches. Experiments were carried out to study the performance by using different combinations of sorbents and elution solvents. Efficiency of alternative extraction methods in terms of fat removal and recovery capability was monitored by gravimetry, TLC, and GC with electron capture detection. Freezing-lipid filtration with solid-phase extraction afforded better clean up efficiency with recoveries in a range of 54.5 to 103.6% with the relative standard deviation of less than 10% for all compounds under investigation.
Assuntos
Gorduras/química , Hidrocarbonetos Clorados/isolamento & purificação , Lipídeos/isolamento & purificação , Resíduos de Praguicidas/isolamento & purificação , Bifenilos Policlorados/isolamento & purificação , Extração em Fase Sólida/métodos , Animais , Brasil , Bovinos , Galinhas , Cromatografia Gasosa/instrumentação , Cromatografia Gasosa/métodos , Cavalos , Hidrocarbonetos Clorados/análise , Lipídeos/análise , Resíduos de Praguicidas/análise , Bifenilos Policlorados/análise , SuínosRESUMO
In the present work experimental conditions were optimized for the analysis of organochlorine traces in water matrix using solid-phase microextraction (SPME) followed by gas chromatography with mass selective detector. The parameters including time of exposure of the fiber in the aqueous sample, fiber type, agitation speed, pH, ionic forces, temperature of adsorption, and time of desorption were evaluated. The best conditions to analyze organochlorine were obtained by using higher than room temperature, agitation of the sample, extraction time of 40 min, and polyacrylate fiber.
Assuntos
Água Doce/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Hidrocarbonetos Clorados/análise , Praguicidas/análise , Poluição Química da Água/análise , Adsorção , Hidrocarbonetos Clorados/isolamento & purificação , Concentração de Íons de Hidrogênio , Praguicidas/isolamento & purificação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Temperatura , Fatores de TempoRESUMO
Owing to limitations of pump-and-treat, several technologies are being investigated for groundwater treatment. One of the most promising is the treatment of contaminants through the use of reactive barriers installed in situ, especially in the case of aquifers contaminated with chlorinated solvents. This work presents results of batch and column tests with metallic iron and some chlorinated solvents (1,2-DCA, 1,1,2-TCA and TCE). Such tests provided means to evaluate the degradation rates of these compounds and their byproducts. It is concluded that the reductive dechlorination with metallic iron can have different results, depending on the type of contaminant. Some contaminants may not present any degradation, or they have a half-life time so high that the use of the reactive barrier technology may not be practical. Furthermore, the formation of chlorinated byproducts, eventually more toxic than the original contaminant and that are not degradable using this same technology, emphasises that the treatment of aquifers should be sequential.
Assuntos
Água Doce/análise , Água Doce/química , Modelos Químicos , Poluentes da Água/isolamento & purificação , Poluição da Água/prevenção & controle , Biodegradação Ambiental , Hidrocarbonetos Clorados/isolamento & purificação , Ferro/química , Cinética , Solventes/isolamento & purificaçãoRESUMO
This study presents the design, monitoring and remediation strategy for a soil vapor extraction (SVE) system installed at an industrial site contaminated with a mixture of organic compounds, in particular 1,2 dichloroethane, carbon tetrachloride and chloroform. The unsaturated zone at the site is very deep and presents near ideal conditions for SVE, with the contaminated portion of the porous media characterized by alluvial deposits of a well graded sand followed by a capillary barrier at 28m of depth, which limited DNAPL downward migration. The soil cleanup time and the optimal removal rates of mass, considering different values of vacuum/discharge applied in the SVE system, have been estimated through the use of numerical sensitivity analysis. Results of the pilot-scale testing activities allowed for the calibration of flow and contaminated mass transport models and the determination, in a preliminary phase, of the infiltrated mass of different compounds.